No amount of caffeine can keep your head from making its way to your desk (no, you’re not sleeping, just resting your eyes). Lunch slips you into a food coma. The 3 p.m. slump feels more like a three-hour grand finale of sleepiness. You go through this cycle day after day. You are always tired.

We went to Carl Bazil, M.D., professor of neurology and director of the Division of Epilepsy and Sleep at Columbia University Medical Center to find out what the heck is going on. “People always come to me wanting sleeping pills, but if you don’t change your daily lifestyle habits to get a good night’s sleep, then nothing will work,” he explains.

Address these bad habits to ensure you get restorative sleep each night so you have enough energy to stay alert at work and power through even the most strenuous workouts.

You have a subpar bedroom environment

In order to fall—and stay—asleep, you’ve got to be comfortable. “It seems obvious, but your bed has to be to your liking, the temperature has to be just right, it’s got to be quiet, and you need to remove anything that can be disruptive to sleep—like pets,” Bazil says.

You’re not winding down

“Technology and devices are really the biggest problems interfering with sleep,” Bazil says. If you’re checking emails and social media right up until you go to bed, your brain thinks it needs to stay awake. It’s even worse if you leave your phone on—if you’re drifting off to sleep and it buzzes or beeps, it startles your body and mind into a frenzied, urgent state of mind. “The other problem is tablets and laptops emit blue wavelength emissions, which interfere with your sleep by blocking the secretion of melatonin—a natural signal that tells your body to go to sleep,” Bazil explains. Ultimately, winding down depends on the individual, so if watching television or reading helps you do that, then that’s OK. The point is your brain needs time to relax if you’re going to sleep effectively.

You’re napping too frequently

Naps are somewhat of a paradox. A two-hour nap in the afternoon may feel amazing in the short term, but it can perpetuate poor sleep habits in the long term. “If you’re tired during the day and you have the opportunity—some workplaces even have pods and those sorts of things—naps can give you some extra energy,” Bazil says. But if it causes you to stay up late, or prevents you from falling asleep, you’re only adding to your sleep debt. Best to keep them short and sweet.

You’re eating too many carbs at lunchtime

“Everyone has a natural dip after lunchtime where they tend to get sleepy—especially if you have a carb-heavy lunch like pasta,” Bazil says. Here’s a simple solution: Eat lean proteins and veggies instead.

You’re eating too little or too much before bed

Bears eat to hibernate all-winter long. You should not follow suit—well, sort of. “In terms of eating before bed, you don’t want to eat a huge meal and experience heartburn or bloating, but you also don’t want to climb into bed starving, because that can be another state of arousal,” Bazil says. There has to be a balance. Grab a light snack around bedtime to keep your stomach from grumbling and your mind from racing.

You’re not getting any tryptophan before bed

The old lure of warm milk isn’t entirely a wives’ tale. “It’s because of the amino acid tryptophan, and the way to stimulate that is through carbohydrates over heavy fats and proteins,” Bazil says. The combination of carbohydrates in milk and the tryptophan in turkey can serve as natural sleep aids—though a strange pre-sleep snack.

You’re trying to catch up on sleep

Finding a technique that helps you shut down, whether it’s reading, yoga, or meditation is essential because fighting fatigue is all about having restorative sleep at night. “You can’t get by on five or six hours of sleep no matter how much you think you’ve adapted to it,” Bazil says. And you have to remember you can’t completely make up for missed sleep during the week over the weekend—unfortunately it doesn’t work that way.

You have social jet lag

You’re probably not familiar with the term, but you definitely do it. “People who have a 9-5 schedule may cheat on sleep during the week, and have a typical bedtime of 11 p.m., but on Friday and Saturday, stay up until 2 a.m.—that’s like going from New York to California every week,” Bazil says. It’s easier for our bodies to delay sleep than it is to fall asleep earlier, but the main problem is Sunday night. “The reason people are wiped on Mondays is because they try to get to bed again at their usual bedtime, but they’re not tired,” Bazil says.

You have sleep apnea

Sleep apnea is so common and very overlooked. It’s hard to know if you have it if you don’t have a bed partner, but other signals of the disorder are no-restorative sleep (meaning you sleep for seven or eight hours, but wake up exhausted), headaches (because you’re not breathing properly in your sleep), and feeling sick after sleeping for long periods of time (because your body isn’t getting enough oxygen). You should see a sleep specialist if your lifestyle and habits are conducive to a good night’s sleep, but you constantly feel fatigued, Bazil suggests.

You’re working out before bed

Though exercising can keep your energy up during the day and help you sleep at night, if you do it at an inopportune time, it can hurt you. “You can’t get off the bike or treadmill and expect to go to bed half an hour later, because your body’s all jazzed up,” Bazil says. It’s better to work out in the morning or right after work so your body has a chance to settle down.